The government-backed Commonwealth Scientific and Industrial Research Organization (CSIRO) developed the site so people can see for themselves how climate-warming gases have increased as a result of human activity.

"The measurements testify to a steady rise in carbon dioxide concentrations in the Earth's atmosphere, mainly caused by the burning of fossil fuels and deforestation," said CSIRO scientist Paul Fraser.

The website, www.csiro.au/greenhouse-gases, has interactive graphs showing the levels of carbon dioxide, nitrous oxide and methane.

Chemicals that deplete the ozone layer are also measured, such as chlorofluorocarbons and halons, with the site updated monthly as new samples are tested.

The data is taken from air samples collected by CSIRO and the Bureau of Meteorology at Cape Grim in Tasmania.

Cape Grim is seen as an important site, as the air sampled arrives there after long trajectories over the Southern Ocean with the air representative of a large area of the southern hemisphere unaffected by pollution sources.

Northern hemisphere air is monitored by Mauna Loa Observatory in Hawaii.

"The graphs we've made available online will enable people to examine the evidence about the major driver of recent climate change," said Fraser.